1. Field of the Invention
The present invention relates to systems which can enclose an object that is sensitive to environmental conditions until it is ready to be launched (or leave) from the enclosure.
2. The Prior Art
Forward closure systems are used as devices to seal enclosures that contain an object, launchable from submerged, underground or surface launchers. Their primary goal is to act as an environmental seal while the launchable object is not in use, and to allow object egress during launch procedures.
In the prior art forward closure systems, the device is designed to be removed prior to launch of the object and is not reusable. In U.S. Pat. No. 3,135,163 to Mechlon et al., an explosive cord ruptures a diaphragm prior to an object launch. The detonation has to happen in a pre-determined pattern such that the debris from the diaphragm will not damage the object as well as the surrounding equipment.
In U.S. Pat. No. 3,742,814 to Kroh, the closure diaphragm is made up of a thin frangible plastic, which can be ruptured by the launched object. However, the drawback with this system is that, the launched object can be damaged while interacting with the plastic diaphragm. In addition, the thin diaphragm might not be strong enough for enclosures submerged at significant depths in water, and cannot withstand the hydrostatic pressure conditions.
U.S. Pat. No. 3,962,951 to Schenk, discloses the use of a hold down locking device to keep the shatterable type closure system in place. The closure may be made of asbestos-reinforced phenolic plastic. However, similarly, this closure system is ruptured by contact with the launched object, which can damage the launched object; moreover, debris generation still remains an issue.
A closure comprising of frangible glass ribs that form a dome shaped closure is disclosed in U.S. Pat. No. 4,301,708 to Mussey et al. A linear-shaped explosive charge arranged in a pre-determined pattern fragments the glass section prior to launch. The issue of excessive debris generation remains a problem with this design.
Another frangible fly-through diaphragm design is disclosed in U.S. Pat. No. 4,498,368 to Doane. This diaphragm is formed from epoxy and fiberglass plies, which are torn in a pre-determined path, during the fly-through launch of an object.